Joystick controls are commonly used on machines having a dual path hydraulic drive. Typically, movement of the joystick in a fore and aft direction controls the forward and reverse drive functions, while moving the joystick from side to side from the neutral position controls the steering function. The joystick is normally spring biased to return to the neutral position when the operator releases the joystick. Optionally, many joysticks used for implements have a detent mechanism to hold the joystick primarily in an extreme actuated position.
One of the problems encountered with the joysticks used for dual path hydrostatic drive machines is that even though the force exerted by the return spring of today's joystick controls is relatively light, such force contributes significantly to operator arm fatigue, particularly when the joystick is held in a forward or a reverse drive position for extended travel periods.
Another problem encountered therewith is such detents have heretofore been capable of only holding the joystick at a particular position. For various reasons, the operator may wish to operate the vehicle at a speed less than maximum speed and thus it would be desirable to be able to retain the joystick at various operating positions. Variable position control levers have been designed to accomplish this task such as that disclosed in U.S. Pat. No. 3,556,270 issued to Comment et al on Jan. 19, 1971. However, this control lever only allows movement of the lever in one plane and is only useful for cable or linkage type control arrangements.
Finally, friction packs are often used to hold a lever at various positions. However the friction force required to hold the lever at the maximum actuated position makes lever modulation difficult. The friction pack force is hard to turn on and off and such devices are not suitable for levers that must be automatically returned to a neutral position before an engine is started. The control lever disclosed in the co-pending application serial number 08/713679 overcomes this problem and is known to work well in most instances. However this arrangement requires that the circular member to be of varying width to aid in holding the lever at the maximum actuated position.
The present invention is directed to overcoming one or more of the problems as set forth above.